This invention relates to tools for dropping balls into a tubing or casing string of a well bore.
In the course of operating downhole tools in an oil or gas well, it is sometimes necessary to release one or more variously sized balls or plugs from the surface into the tubing or casing string. The devices used for dropping balls or plugs are sometimes referred to as ball droppers, ball dropping heads, or cementing heads, plug containers or ball dropping heads.
A common method of releasing balls in these types of devices involves the use of linear actuators which are operated by either being rotated by a screw mechanism from the outside of the container or by a remote controlled piston on the outside of the container. The nature of these linear actuators is such that they protrude from the side of the container far enough to be cumbersome to use and are sometimes a problem on the rig floor. Because of the extension of the linear actuators, the operator may not be able to rotate the container because the distance between the bails is not sufficient to clear the actuators and allow them to rotate freely.
Additionally, prior art ball dropping tools must be pre-loaded, i.e., they cannot be loaded with balls when the tools are installed in a pressurized string of tubing or tubulars. Accordingly, where additional balls are required to be dropped while the tools are in the drill string, then, before loading the dropping tool, pressure must be relieved from the string of tubing or tubulars. Furthermore, in many cases prior art ball droppers must be removed from the line when being loaded with balls.
Various embodiments solve one or more of these problems by providing a compact mechanism for releasing balls or other items into the tubing or casing string even while the string pressurized. A tool is provided permitting easy release of one or more balls. Additionally, at least a portion of the ball loading section of can be fluidly sealed from the remainder of the tool.
While certain novel features of this invention shown and described below are pointed out in the annexed claims, the invention is not intended to be limited to the details specified, since a person of ordinary skill in the relevant art will understand that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation may be made without departing in any way from the spirit of the present invention. No feature of the invention is critical or essential unless it is expressly stated as being “critical” or “essential.”